NIR stands for Near Infrared Reflection and designates a method of analysis, in which the contents of various components of materials, e.g., water and protein, can be determined by a quite brief infrared irradiation of a sample portion of a few grams of the material. NIR analysis devices for general laboratory applications, e.g., in feedstuff factories or mixing establishments, have already been developed.
In the use of such devices, a homogenized sample of a few cubic centimeters is placed in a particular test cup, which is then mounted against a quartz disc on an analyzer head of the device, from which the surface of the sample is irradiated; the reflected rays are picked up by a particular detector which supplies electrical signals representative of the various components of the material. Before the next analysis, the equipment must be cleaned carefully, usually by washing with an organic solvent, as remnants of the material sample in the test cup or on the quartz disc may cause the next analysis to be inaccurate.